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2x^(2) + 3x - alpha = 0 " has roots "-2 ...

`2x^(2) + 3x - alpha = 0 " has roots "-2 and beta " while the equation "x^(2) - 3mx + 2m^(2) = 0 " has both roots positive, where " alpha gt 0 and beta gt 0.`
`Delta PQR, angleR=pi/2. " If than "(P/2) and tan (Q/2) " are the roots of the equation " ax^(2) + bx + c = 0 ,` then which one of the following is correct ?

A

`a+b=c`

B

`b+c=a`

C

`c+a=b`

D

`b=c`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the given problem step by step, we will break it down into manageable parts. ### Step 1: Understand the given equations and roots We have two equations: 1. \( 2x^2 + 3x - \alpha = 0 \) with roots \( -2 \) and \( \beta \). 2. \( x^2 - 3mx + 2m^2 = 0 \) with both roots positive. ### Step 2: Use Vieta's formulas for the first equation According to Vieta's formulas, for the first equation: - The sum of the roots \( (-2 + \beta) = -\frac{b}{a} = -\frac{3}{2} \) - The product of the roots \( (-2 \cdot \beta) = \frac{c}{a} = -\frac{\alpha}{2} \) From the sum of the roots: \[ -2 + \beta = -\frac{3}{2} \implies \beta = -\frac{3}{2} + 2 = \frac{1}{2} \] From the product of the roots: \[ -2 \cdot \frac{1}{2} = -\frac{\alpha}{2} \implies -1 = -\frac{\alpha}{2} \implies \alpha = 2 \] ### Step 3: Analyze the second equation Now, we look at the second equation \( x^2 - 3mx + 2m^2 = 0 \). For this equation, we need both roots to be positive. Using Vieta's formulas again: - The sum of the roots \( r_1 + r_2 = 3m \) (must be positive) - The product of the roots \( r_1 \cdot r_2 = 2m^2 \) (must be positive) Since both roots are positive, we conclude that: - \( 3m > 0 \implies m > 0 \) - \( 2m^2 > 0 \implies m \neq 0 \) ### Step 4: Analyze the triangle PQR Given that triangle PQR has \( \angle R = \frac{\pi}{2} \), we can find the angles \( P \) and \( Q \): \[ P + Q = \frac{\pi}{2} \] ### Step 5: Find the roots of the quadratic equation The roots of the equation \( ax^2 + bx + c = 0 \) are given as \( \tan\left(\frac{P}{2}\right) \) and \( \tan\left(\frac{Q}{2}\right) \). Using the sum and product of the roots: - Sum of roots: \[ \tan\left(\frac{P}{2}\right) + \tan\left(\frac{Q}{2}\right) = -\frac{b}{a} \] - Product of roots: \[ \tan\left(\frac{P}{2}\right) \tan\left(\frac{Q}{2}\right) = \frac{c}{a} \] ### Step 6: Apply the tangent addition formula Using the tangent addition formula: \[ \tan\left(\frac{P}{2} + \frac{Q}{2}\right) = \tan\left(\frac{\pi}{4}\right) = 1 \] Thus, \[ \tan\left(\frac{P}{2}\right) + \tan\left(\frac{Q}{2}\right) = 1 \cdot \left(1 - \tan\left(\frac{P}{2}\right) \tan\left(\frac{Q}{2}\right)\right) \] ### Step 7: Set up the equation From the above, we derive: \[ -\frac{b}{a} = 1 \quad \text{and} \quad \frac{c}{a} = \tan\left(\frac{P}{2}\right) \tan\left(\frac{Q}{2}\right) \] ### Step 8: Conclusion After substituting and simplifying, we find that: \[ a + b = c \] ### Final Answer Thus, the correct relation is: \[ \boxed{a + b = c} \]
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